[AndyB] Convert image 5.2

Added code to prevent server error if embedded meta data is empty.

Updated regex to fix issue with multiple IMG tags on same line.

Fixed issue with try / catch code

• Fixed issue with converting images in conversations.

• Added 'Convert conversations' to options page.

• Added 'Exclude domains' to options page.

Now retains IMG bbcode options.

Now supports webp images by converting them to jpg.

• Added Extension check to options page.